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Old 09-18-2005, 06:55 AM   #90
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Join Date: Apr 2003
Location: Maplewood, NJ
Posts: 446
My Ride: 2001 540i 6-Speed
Originally Posted by Asmodeus
I disagree because i have done numerous 150-30 km/h (sorry, don't feel like converting to mph) 'stops' at the track where I go lapping every week, and the HP+ require a much shorter distance than the HPS.

Friends of mine have tried the Gransport GS3 and all agree that the stopping distance is less than with the HP+ which is less than the HPS.

In coefficient of friction comparisons. GS3 > HP+ > HPS.

Don't mean to be a pain in the ass, but what you are saying contradicts what we experience at the track every week. Unless if I am not understanding you correctly.
That's because the HPS are quickly fade limited at the track, whereas the HP Plus (under the conditions imposed by your skill and equipment level) are not. If you read my post carefully, I'm saying that there will be no difference in stopping distance between a street and race pad during a single stop comparison. Under those conditions, you are not fade limited. When you are not fade limited, you are always tire limited.

I should probably add one more caveat. If, during that single stop comparison, the race pads heat up enough to get into their operating zone, you may end up having to lift off the brake pedal slightly to avoid locking up the wheels or engaging ABS. Unlike street pads, which tend to have a flat torque curve when cold and then lose friction when MOT is exceeded, race pads have a lower friciton level (often until about 300-400 degrees F) and then suddenly jump up to a higher friction level. You can feel this when bedding them in, usually on the 3rd or 4th slowdown. It feels like someone flipped the "power brakes" switch.

Getting back to the HP Plus pads, I urge you to swap them out (for track use) for either a true race pad or a street pad that doesn't have such a dangerous slope to the friction vs temperature curve. You apparently haven't bumped up against the HP Plus pads' MOT yet, but as you continue to improve your skills and your equipment level, you will eventually. At that time, you may find yourself up against a tire barrier or at least deep in gravel, picking stones out from between your tire sidewalls and the tire beads.
Dave Zeckhausen
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